This invention relates generally to sleeping bags, and more specifically to a sleeping bag with a vent opening selectively adjustable between an open position and a closed position for venting the inner volume of a sleeping bag.
Consumers face a difficult task in finding a sleeping bag that meets their needs over a wide variety of ambient temperatures in which the bag is intended to be used. Mummy bags, which generally minimize internal volume, are shaped with a lateral taper to approximately contour the body of a person. Accordingly, these bags effectively conserve heat by decreasing air movement within the bag. As a result, mummy-type sleeping bags are well suited for use in outdoor, cold ambient temperatures. A drawback to mummy bags is that some people feel discomfort because they become too warm or the air within the bag becomes stagnant. In addition, the relatively snug fit of these bags reduces the user's range of motion, especially near the foot end of the sleeping bag.
Rectangular-type sleeping bags have a generally constant lateral dimension providing generally good knee and foot room and freedom of motion. While rectangular bags are generally more spacious than mummy bags, a drawback is that their larger internal volumes make them thermally inefficient. As a result, rectangular bags are well suited for use indoors or in milder outdoor temperatures. When used in colder environments, persons using rectangular bags can more easily become chilled, especially toward their feet.
Unfortunately, sleeping bag designs typically incorporate a one-type-fits-all approach. People who want to use bags in both colder and milder temperature environments typically either purchase two bags (i.e., a mummy bag and a rectangular bag) at considerable expense, or get by with one bag designed for one environment but which is less than ideal in the other environment. In addition, some users would prefer a bag that allowed the stagnant air within the bag to escape and be replaced with fresh, ambient air. Unfortunately, no single sleeping bag is available that provides all of these characteristics.